Here

Jimin is scared of thunder and he's all alone.

Jungkook figures his motorcycle isn't the safest place if he wants to avoid the nearing lightning.

Or...

Jimin needs a cuddle buddy and the stranger on his porch seems like a cross between a bunny and a bodybuilder. On Jungkook's side of things, Jimin is really cute when he's scared and he really doesn't hate the idea of cuddling for a while.

*in editing, but I swear I'm just cleaning it up*